Hi, I have an application where I have to switch on/off 2 3.3V low power=20 devices(~50mA max combined) with a 3.3V MCU signal. I am currently=20 using a TP0610K that I have lying around with the following=20 connections. Source - 3.3V Gate - 50K pullup to 3.3V, and MCU control signal Drain - 1M pulldown and device Vcc
This seems to work, but according to the TP0610K datasheet
*According to the Rds(on)-Vgs graph, Rds(on) rises sharply at about=20 Vgs =3D 5V
Now, while the switch seems to work now, there are a couple of things=20 that worry me.
1) The Id(on) of 50mA is probably lower when Vgs, Vds =3D -3.3V, and=20 this may be a problem since my devices consume about 50mA max
2) Rds(on) rises almost to an asymptote when Vgs < 5V
With that said, I looked at a few other mosfets that I could drop into=20 my existing design, and came up with the following: Fairchild FDV304P - Vth -0.86V, Id -460mA, Rds(on) 1ohm@-3.3V Vgs Fairchild FDV302P - Vth 1V, Id -120mAm Rds(on) ~8ohm@-3.3V Vgs ON NTR1P02LT1 - Vth -1V, Id -1.3A, Rds(on) curve bends at -4V Vgs,=20
0=2E19ohm-2.5V Vgs ON NTR2101P Vth -1V, Id -3.7A, Rds(on) 0.05ohm@-3.3V Vgs ON NTR4101P - Vth -0.72V, Id -3.2A=EF=BC=8C Rds(on) 0.09ohm@-2.5V Vgs Vishay Si2323DS - Vth -1V, Id -4.1A, Rds(on) 0.035ohm@-3.3V Vgs Vishay Si2301BDS - Vth -0.95V, Id -2A?, Rds(on) 0.1ohm@-3.3V Vgs
There are a few more, but I just want to make sure if I have the right=20 idea. Basically what I'm thinking is that I need a mosfet that has the=20 following characteristics:
1) low threshold voltage(all the above have Vgs(th) >=3D -1V
2) Sufficient Id(-120mA and less should be sufficient?)
3) Low Rds(on)(single digit, or even